Considerable effort has been directed toward improvement of the safety of seat assemblies which are employed in various types of vehicles and the comfort of seat assemblies which are used in vehicles and in stationary applications. Typical of such effort are the seat assemblies set forth in my U.S. Pat. Nos. 4,650,249; 5,244,252; 5,460,427; 5,558,399 and 5,735,574. Such prior art seat assemblies have sought to improve seating safety and comfort by designing seat motion in a manner controlling body posture and the forces generated in a muscular-skeletal system during rapid vehicle deceleration. Numerous other patents have been directed to the same general goals.
My U.S. Pat. No. 4,650,249, for example, discloses a seat assembly in which the seat is mounted to move along a concave arcuate path having a center of rotation proximate the center of mass of the user. In U.S. Pat. Nos. 5,244,252 and 5,460,427 the movable seat moves away from a lumbar support member and thereby creates a gap in the lower lumbar region that promotes reversing of the lumbar spine. In my U.S. Pat. No. 5,735,574 the lumbar support member has been added which is linked for movement with the seat. The backrest in this patent, however, is fixed, and the lumbar support member moves up and down inside the backrest frame separating the lower part of the backrest between the upper edge of the lumbar and backrest frame. In U.S. Pat. Nos. 5,558,399 and 5,735,574, the FIG. 3 embodiment of these patents includes seat motion which is arcuate in a downward direction, which is undesirable from the safety standpoint.
In addition to my above-noted prior patents U.S. Pat. No. 6,030,043 to Habedank and U.S. Pat. No. 5,961,073 to Whitmann disclose seat assemblies suitable for use in motor vehicles which include movable slots. Thus, the patent to Habedank discloses a seat which is pivoted to the seat base at an adjustable pivot location. The backrest is independently tiltable and also coupled to the seat so that the backrest will be automatically tilted as the seat moves backward and forward, as driven by an electric motor drive. The design is particularly well suited for use in the back seat of an automobile.
The patent to Whitmann, U.S. Pat. No. 5,961,073 discloses a seat assembly for aircrafts in which the bottom seat cushion is guided by rollers in tracks to move forward and upward upon an inertial load. This is combined with a lap belt to limit head excursions on crashes.
The present seat assembly and method include a seat which is mounted for movement along an upwardly concaved arcuate path having a center of rotation proximate the center of mass of the occupant seated on the seat. This type of seat mounting is broadly known and described in my prior patents. In the present invention, however, a backrest is provided which also is linked or coupled for motion that is dependent upon seat motion at the lower end and coupled by an upright slide plane supporting said backrest at the upper end. This linking, produces a self-adjusting effect which realigns the seat assembly in response to changes of body posture by automatically and synchronously seeking equilibrium against the direction of gravitational acceleration and the direction of vehicle longitudinal accelerations. In extreme cases, during frontal or rear impact of a vehicle, the seat provides restraining safety motion to reduce injury.
The backrest frame also can be formed to recline so that the sliding motion of the backrest can be selectively reclined. Moreover, the present seat assembly can work in conjunction with other restraints such as headrests, belts, airbags, lower leg cushions and knee bolsters. Still further the seat assembly of the present invention can be adjusted and controlled to fit different sizes of users in many different postures, such as; an upright or slightly reclined posture for driving; a forward leaning posture for reaching controls or auxiliary equipment; a semi-reclined posture, as may be required in low vehicle cabins; and an extremely reclined seated posture, such as may be employed for sleeping in airliners or the like.
Accordingly, it is an object of the present invention to provide a seat assembly and method which provide enhanced safety and comfort for vehicular and stationary seating application.
Another object of the present invention is to provide a seat assembly and method which provide enhanced safety for vehicle applications in which frontal or rear impacts rebounding accelerations and diagonally offset crashes can cause injurious forces.
A further object of the present invention is to provide a seat assembly and method which can be used to provide enhanced comfort for a wide variety of seating postures.
Another object of the present invention is to provide a seat assembly having improved safety and comfort which is economical to construct, durable and can be employed in a wide range of applications.
The seat assembly and method of the present invention have other objects and features of advantage which will become apparent from, or are set forth in more detail in the accompanying drawings and descriptions of the Best Mode of Carrying out the Invention.